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• How to decide raw h264 using pyav ?

  26 septembre 2016, par Winston Chen

  I am playing pylive555 (Please refer to this article.) against my web cams. I am able to get the bytes of each frame (be it i frame, p frame, or b frame) out using the code listed in the article.

  However, what comes next will be to decode the bytes into an actual frame image or numpy array (just i frame, p frame, or b frame themselves, not applying delta onto the i frames when it comes to p frame or b frame).

  I did some research online and found that a we might be able to use avcodec_decode_video2 function like it’s said in this post. Has anybody done this with pyAv ? Do you mind sharing how you did it ?

• How to setup live video stream from webcam to the server, and then beyond ? [closed]

  15 mai 2020, par Parth Sarthi

  I have an application, that is written in Node and Nuxt, to host online exams. My clients are now demanding youtube like livestream for their students. I can't use WebRTC because there will be thousands of students watching the live video, so I don't think teacher's bandwidth will be able to deliver that.

  



  Now I want to know what other options do I have ? How do I send video stream from teacher's laptop to the server in real time ? I am assuming getUserMedia ? Then how do I convert the live stream incoming from the teacher into something like HLS ? I am assuming ffmpeg ? but what commands will do that actually ? cause i can't seem to find any which will take in Media Stream and convert it into HLS. And lastly how do I server it back to the students.

  



  I have already setup the live chat for every classroom with socket.io so I am stuck here.

  


• Capture camera + mic and encode to h264/aac on macOS

  16 décembre 2018, par Flock Dawson

  I’m having trouble capturing and encoding audio+video on-the-fly on macOS.

  I tried two options :

  1. ffmpeg

     ffmpeg -threads 0 -f avfoundation -s 1920x1080 -framerate 25 -I 0:0 -async 441 -c:v libx264 -preset medium -pix_fmt yuv420p -crf 22 -c:a libfdk_aac -aq 95 -y

  2. gstreamer

     gst-launch-1.0 -ve avfvideosrc device-index=0 ! video/x-raw,width=1920,height=1080,framerate=25/1 ! vtenc_h264 ! queue ! mp4mux name=mux ! filesink location=out.mp4  osxaudiosrc device=0 ! audio/x-raw ! faac midside=false ! queue ! mux.

  The ffmpeg option works, but only for lower resolutions. With higher resolutions, the Mac mini (2018 gen) can’t do the heavy lifting. I think because I installed ffmpeg with brew, so it wasn’t compiled on my machine, meaning it doesn’t use the h264 hardware encoder in the Mac ?

  The gstreamer option works as well, but there’s a slight audio/video sync issue (audio is 100ms ahead of the video). I can’t seem to add delay to the GStreamer queue (it ignores it) :

  queue max-size-buffers=0 max-size-time=0 max-size-bytes=0 min-threshold-time=100000000

  Anyone who has any experience with this ? Thanks !